Liquid trap with integral jet pump

ABSTRACT

An assembly is provided that integrates a jet pump with a liquid trap to drain liquid fuel from vapor flow, such as vapor vented from a fuel tank. The assembly includes a housing that has a liquid trap configured to trap liquid carried in vapor flowing through the housing. A jet pump has a venturi nozzle and is in selective fluid communication with the liquid trap so that liquid flow through the venturi nozzle induces draining of the liquid trap.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of and claims priority toU.S. patent application Ser. No. 13/334,529, filed Dec. 22, 2011, whichis hereby incorporated by reference in its entirety.

TECHNICAL FIELD

The present teachings generally include a liquid trap drainable via ajet pump.

BACKGROUND

Fuel tank vapor and emission control systems can be used to control theflow of fuel vapors from a vehicle fuel tank and also to control therelative pressure of the fuel tank. Vapors may be vented to a canisteror other similar vapor recovery control structure and stored untilprovided to an engine.

SUMMARY

An assembly is provided that integrates a jet pump with a liquid trap todrain liquid fuel from vapor flow, such as vapor vented from a fueltank. The assembly includes a housing that has a liquid trap configuredto trap liquid carried in vapor flowing into the housing. A jet pump hasa venturi nozzle and is in selective fluid communication with the liquidtrap so that liquid flow through the venturi nozzle induces draining ofthe liquid trap.

A valve can be included in the housing. The valve is configured toprevent draining of the liquid trap by the jet pump when a pressuredifferential created by liquid flow through the venturi nozzle is belowa predetermined level, and to allow fluid communication between the jetpump and the liquid trap when the pressure differential is above thepredetermined level. The valve allows draining of the liquid trap to thejet pump through an opening in the housing while preventing liquid fuelfrom entering the trap through the opening.

A pressure reducer can be upstream of the venturi nozzle. The pressurereducer is configured to reduce pressure and increase velocity of liquidflow to the venturi nozzle. The pressure reducer can include a series ofplugs positioned to define a tortuous flow path for liquid flow to theventuri nozzle, thereby reducing pressure and increasing velocity of theliquid flow.

The above features and advantages and other features and advantages ofthe present teachings are readily apparent from the following detaileddescription of the best modes for carrying out the present teachingswhen taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration in cross-sectional view of a liquidtrap assembly with a liquid trap and an integrated jet pump, taken atthe lines 1-1 in FIG. 2.

FIG. 2 is a schematic perspective illustration of the liquid trapassembly assembly of FIG. 1.

FIG. 3 is a schematic perspective top view illustration of the liquidtrap assembly of FIG. 1 with a cap removed.

FIG. 4 is a schematic perspective side view illustration of the liquidtrap assembly of FIG. 1.

FIG. 5 is a schematic illustration in cross-sectional view of analternative embodiment of a jet pump for the liquid trap assembly ofFIG. 1, taken at lines 5-5 in FIG. 7.

FIG. 6 is a schematic illustration in perspective view of plugs forminga pressure reducer in the jet pump of FIG. 5.

FIG. 7 is a schematic perspective cross-sectional view of the jet pumpof FIGS. 5 and 6, taken at lines 7-7 of FIG. 5.

FIG. 8 is a schematic illustration of a vehicle fuel system includingthe liquid trap assembly of FIG. 1.

DETAILED DESCRIPTION

Referring to the drawings, wherein like reference numbers refer to likecomponents throughout the several views, FIG. 1 shows a liquid trapassembly 10 that efficiently drains liquid collected from vapor. Theliquid trap assembly 10 has a housing 12. The housing 12 has a firstport, referred to as a vapor flow inlet 14 and a second port, referredto as a vapor flow outlet 16 (shown in FIG. 2) in fluid communicationwith an interior cavity 18 formed at least in part by the housing 12.Vapor flows from the vapor flow inlet 14, through the cavity 18, to thevapor flow outlet 16. Liquid entrained in the vapor flow is collected ina liquid trap 20 formed by the housing 12 at the bottom of the housing12. The outlet 16 can be replaced by an outlet valve, or the housing 12can have no outlet. Either or both of the housing 12 and a cap 32described below (in embodiments that have a cap 32) can have featuresthat promote separation of liquid and vapor, such as baffles and ribs.

The liquid trap assembly 10 may be used in many applications. In oneapplication described herein, the liquid trap assembly 10 is used in afuel vapor recovery system 21 on a vehicle, shown schematically in FIG.8. The vehicle can be a diesel, gasoline, or hybrid application. Vaporis vented from a fuel tank 22 containing liquid fuel through a vaporvent valve 26 that may provide pressure relief, rollover shutoff, andother functions. Vapor flows from the vapor vent valve 26 to the liquidtrap assembly 10 through inlet 14 and exits through an outlet 16 to avapor recovery device, such as a canister 28 filled with carbongranules. The canister 28 is periodically purged to an engine 30. Theliquid trap assembly 10 is shown mounted within the fuel tank 22.Alternatively, the liquid trap assembly 10 can be external to the fueltank 22.

FIG. 2 shows a cap 32 that closes a top portion of the cavity 18 of FIG.1 by connecting to the housing 12 with tabs 34 of the cap 32 held atretainers 37 of the housing 12. The housing 12 can instead be aone-piece component without a separate cap 32. The housing 12 forms afirst opening 35 in a sidewall adjacent to the liquid trap 20. Theopening 35 is selectively closed by a check valve 36. Any type of valvecan be used to close the opening 35, or there can be no valve at theopening 35. The opening 35 is best shown in FIG. 4, in which the checkvalve 36 of FIG. 1 is removed. The check valve 36 includes a valve body38 and a spring 40 that biases the valve body 38 into the first opening35 to close the opening 35 and separate the cavity 18 and liquid trap 20from a valve cavity 42 in which the spring 40 and valve body 38 aremovable, as described herein. When the check valve 36 closes the opening35, it also prevents liquid from entering the liquid trap 20 through theopening 35. The valve body 38 is generally annular and has agenerally-cone-shaped end that extends into the chamber 18. The spring40 has a diameter that fits inside the generally annular valve body 38.A valve body with a different shape can also be used. For example, aball valve may be used to close the opening 35.

The liquid trap assembly 10 includes a jet pump 44. A first component 45of the jet pump 44 includes an inlet portion 47 forming a passage withan inlet 46, a venturi nozzle 48 and an end plate 50 integrally formedwith one another. An interface of a groove 52 at an end of the firstcomponent 45 and an extension 54 of the housing 12 forms a labyrinthseal 56 that substantially prevents liquid and vapor from passing out ofthe valve cavity 42, except for through a second opening 62, asdescribed below. The extension 54 is also shown in FIG. 4. Anotherannular seal 58 between the first component 45 and a flange 60 of thehousing 12 further prevents liquid and vapor from escaping the housing12. Although a labyrinth seal 56 and an annular seal 58 are shown, othertypes of seals can instead be used. In lieu of seals, the firstcomponent 45 can be welded or otherwise connected to the housing 12. Asecond opening 62 at a lower portion of the housing 12 forms a gap inthe labyrinth seal 56 adjacent the nozzle 48. The first component 45 ofthe jet pump 44 connected to the housing 12 closes the valve cavity 42and provides a surface 64 on which the spring 40 rests. The only exitfrom the valve cavity 42 is the opening 62.

A lower portion of the housing 12 forms a portion of a jet pump 44, asdescribed below, including a cavity 66 around the nozzle 48 that is alsoin fluid communication with the opening 62. The housing 12 also forms anoutlet portion 68 of the jet pump 44, with a channel 67 between thecavity 66 and an outlet 70. The channel 67 of the outlet portion 68 canbe designed to function as a diffuser to increase pressure and reducevelocity of the fluid. Instead of the housing 12 forming a channel 67that functions as a diffuser, a tube configured to function as adiffuser can be connected to receive flow from the cavity 66. The cavity66 and channel 67 serve as a mixing chamber at the outlet of the nozzle48.

The vapor flow inlet 14, the second port 16, the inlet 46 and the outlet70 are formed by barbed connectors 69A, 69B, respectively, so thatconnection to other components of the fuel vapor system 21 of FIG. 8 issimplified. For example, the barbed connector 69A forming inlet 14 isconnected to vapor tubing in communication with the vapor vent valve 26.The barbed connector 69B forming the outlet 16 is connected to thecanister 28 via tubing to serve as a vapor outlet. Other types ofconnectors or structure for making connections, such as quick-connectports, can be used instead of barbed connectors. The inlet 46 of the jetpump 44 is connected by tubing 76 to a fuel pump 72 submerged in theliquid fuel 73. The fuel pump 72 is also connected to the engine 30 viafuel discharge tubing 71. Fuel is discharged from the fuel pump 72 atrelatively high pressure through the fuel discharge tubing 71. Thetubing 76 branches from the fuel discharge tubing 71, providingrelatively high pressure liquid fuel flow to the inlet portion 46.

Referring again to FIG. 1, fluid flowing out of the nozzle 48 creates avacuum or at least a relatively low pressure area in the cavity 66adjacent the opening 62. Pressure is also reduced in the cavity 42 dueto the vacuum or low pressure in the cavity 66, creating a pressuredifferential across the valve body 36, as pressure in the cavity 42 islower than pressure in the cavity 18. When the pressure differentialreaches a predetermined level such that a force is created by thepressure differential on the area of the valve body 38 exposed to thecavity 18, and the force is greater than the force keeping the checkvalve 36 shut, in this case the force of the spring 40, the valve body38 will move toward the surface 64 of the end plate 50, compressing thespring 40 and establishing fluid communication between the liquid trap20 and the opening 62. The jet pump 44 is a fuel discharge assemblywhich has the propelling mechanism, due to the pressure differential andjet action, to discharge liquid fuel in the trap 20 to the fuel tank 22.

The jet pump 44 utilizes high pressure fluid from the fuel pump 72 whichflows through the nozzle 48 with a high velocity. The flow through thenozzle 48 is referred to as the primary flow or primary stream. The highvelocity fluid leaving the nozzle 48 creates a low pressure or a vacuumin the area adjacent the nozzle 48, such as at the opening 62. Thepressure differential between the high pressure fluid exiting the nozzle48 and the portion of the cavity 66 adjacent the nozzle 48 induces flow,such as through the opening 62, referred to as an induced stream orsecondary flow. The pressure of the liquid increases as the flow travelsthrough the cavity 66. In some embodiments of the jet pump 44, theoutlet portion 68 with channel 67 is designed to function as a diffuserto increase pressure and reduce velocity of the fluid. Many factorsaffect the performance and efficiency of the jet pump 44, includingfluid molecular weight, feed temperature, position of the nozzle 48,throat dimension, motive velocity, Reynolds number, pressure ratio,specific heat ratio, and the angle between the motive and inducedstream.

FIG. 5 shows another embodiment of a jet pump 144 that can be used inplace of the jet pump 44 in FIG. 1. The jet pump 144 has a mountinginterface 172 at which it is designed to be fastened to the housing 12.Accordingly, in this embodiment, the end plate 50 of FIG. 1 would be aseparate component from the jet pump 144, and the end plate 50 would bemodified to include a fastener opening aligning with fastener openings174 of the jet pump 144 shown in FIG. 7. Alternatively, the jet pump 144could be made integral with the housing 12 and end plate 50.

The jet pump 144 has a pressure reducer 178 located in a passage formedby an inlet portion 147, downstream of the inlet 146 and upstream of thenozzle 148. The pressure reducer 178 can instead be located furtherupstream of the jet pump 144 such as in a vent line leading to the jetpump 144. The pressure reducer 178 reduces pressure and volume flow rateof fluid flow from the inlet 146 to the nozzle 148, while increasingvelocity of flow through the nozzle 148. The pressure reducer 178 can bea series of plugs 180 within the inlet portion 147. The plugs 180 aregenerally cylindrical in the embodiment shown, but can have othercross-sectional shapes. Each plug 180 has an axial opening 182 and asector opening 184 in fluid communication with one another. Theunderside of each plug 180 in FIG. 6 has another axial opening (notshown) in fluid communication with a gap 186 between the plug 180 andthe next upstream plug 180. The gap 186 is then in fluid communicationwith axial opening 182 and the sector opening 184 of the upstream plug180. In this manner, a tortuous flow path is established by the pressurereducer 178 in the inlet portion 147 by requiring fluid to flow inalternate directions through the axial openings 182 to the sectoropenings 184 of each plug 180 in order to reach the nozzle 148. Thetortuous flow path proceeds axially through an axial opening 182, thenclockwise along a portion of a circle through the sector opening 184,then axially again through an axial opening 182 on an underside of theplug 180, then perpendicularly to the axial opening 182 of the next plug180, to the next sector opening 184, etc. A jet pump 144 with a pressurereducer 178 increases the draining rate of the liquid trap 20 of FIG. 1by increasing the jet action.

Referring again to FIG. 5, an outlet portion 168 of the jet pump 144 hasa channel 167 between a cavity 166 and an outlet 170. The cavity 166 isadjacent the nozzle 148. The channel 167 of the outlet portion 168 canbe designed to function as a diffuser to increase pressure and reducevelocity of the fluid. The channel 167 serves as a mixing chamber at theoutlet of the nozzle 148. The channel 167 flares outward in thedirection of flow at a distal portion 169 to function as a diffuser,further reducing velocity and pressure of the fluid.

By utilizing the jet pump 144, a higher draining capacity of the liquidtrap 20 of FIG. 1 can result, as a greater pressure reduction withhigher jet action is achieved. Further, the pressure reducer 178 and thediffuser formed by the distal portion 169 help to reduce the likelihoodof cavitation in the fluid by reducing pressure. Because flow rate isreduced by the pressure reducer 178, the opening at the tip of thenozzle 148 can be larger while still achieving a desired flow velocityand pressure differential. A larger diameter nozzle tip helps to avoidblockage in the flow.

While the best modes for carrying out the many aspects of the presentteachings have been described in detail, those familiar with the art towhich these teachings relate will recognize various alternative aspectsfor practicing the present teachings that are within the scope of theappended claims.

1. An assembly comprising: a housing having a liquid trap configured totrap liquid carried in vapor flowing into the housing; and a jet pumphaving a venturi nozzle and in selective fluid communication with theliquid trap so that liquid flow through the venturi nozzle inducesdraining of the liquid trap.
 2. The assembly of claim 1, furthercomprising: a valve configured to prevent draining of the liquid trap bythe jet pump when a pressure differential created by liquid flow throughthe venturi nozzle is below a predetermined level, and to allow fluidcommunication between the jet pump and the liquid trap to at leastpartially drain the liquid trap when the pressure differential is abovethe predetermined level.
 3. The assembly of claim 2, wherein the housinghas an opening adjacent the venturi nozzle; and wherein the valveincludes: a valve body; and a spring biasing the valve body to a closedposition and having a spring force that is overcome by the valve bodywhen the pressure differential is above the predetermined level, therebyallowing the liquid trap to drain to the jet pump through the opening inthe housing.
 4. The assembly of claim 1, wherein the jet pump is mountedto the housing; and wherein the housing has an opening substantiallyadjacent the venturi nozzle.
 5. The assembly of claim 1, furthercomprising: a pressure reducer upstream of the venturi nozzle configuredto reduce pressure and increase velocity of liquid flow to the venturinozzle.
 6. The assembly of claim 5, wherein the pressure reducerincludes a series of plugs positioned to define a tortuous flow path forliquid flow to the venturi nozzle, thereby reducing pressure andincreasing velocity of the liquid flow.
 7. The assembly of claim 6,wherein the plugs are generally cylindrical and have axial and sectoropenings that form the tortuous flow path.
 8. The assembly of claim 1,wherein the jet pump has a mixing chamber and a diffuser downstream ofthe venturi nozzle.
 9. The assembly of claim 1, wherein the housing andthe jet pump connect to one another at an interface that forms alabyrinth seal.
 10. A liquid trap assembly for a fuel vapor recoverysystem of a fuel tank that has a fuel pump configured to provide liquidfuel flow comprising: a housing having a first port and a second portand forming a liquid trap configured to trap liquid carried in vaporflowing from the first port to the second port through the housing tothe fuel vapor recovery system; wherein the housing has an opening; ajet pump having a venturi nozzle mounted to the housing adjacent theopening in the housing and in fluid communication with the fuel pump sothat the fuel pump pumps liquid fuel through the venturi nozzle; and avalve positioned in the housing and configured to prevent draining ofthe liquid trap through the opening when a pressure differential createdby liquid fuel flow through the venturi nozzle is below a predeterminedlevel, and configured to move to establish fluid communication betweenthe jet pump and the liquid trap through the opening when the pressuredifferential created by liquid fuel flow through the venturi nozzle isabove the predetermined level, the liquid fuel flow through the venturinozzle thereby inducing draining of the liquid trap through the openingin the housing.
 11. The liquid trap assembly of claim 10, wherein thejet pump has an inlet in fluid communication with the fuel pump and apressure reducer between the inlet and the venturi nozzle.
 12. Theliquid trap assembly of claim 11, wherein the pressure reducer includesa series of plugs positioned to define a tortuous flow path for liquidfuel flow to the venturi nozzle, thereby reducing pressure andincreasing velocity of the liquid fuel.
 13. A system comprising: a fueltank having a fuel pump; an engine to which fuel is provided through afuel discharge line from the fuel pump; a fuel vapor recovery device; avapor vent valve operatively connected to the fuel tank and operable tocommunicate fuel vapor from the fuel tank to the vapor recovery device;a liquid trap assembly operatively connected to the fuel tank andhaving: a housing having a liquid trap configured to trap liquid carriedin the fuel vapor flowing from the vapor vent valve into the housing;and a jet pump operatively connected to receive fuel from the fueldischarge line; and wherein the jet pump has a venturi nozzle and is inselective fluid communication with the liquid trap so that fuel flowthrough the venturi nozzle induces draining of the liquid trap.
 14. Thesystem of claim 13, further comprising: a valve positioned in thehousing and configured to prevent draining of the liquid trap throughthe opening when a pressure differential created by fuel fuel flowthrough the venturi nozzle is below a predetermined level, andconfigured to move to establish fluid communication between the jet pumpand the liquid trap through the opening when the pressure differentialcreated by fuel flow through the venturi nozzle is above thepredetermined level, the fuel flow through the venturi nozzle therebyinducing draining of the liquid trap through the opening in the housing.15. The liquid trap assembly of claim 13, further comprising: a pressurereducer operatively connected between the fuel pump and the venturinozzle; and wherein the pressure reducer includes a series of plugspositioned to define a tortuous flow path for liquid fuel flow to theventuri nozzle, thereby reducing pressure and increasing velocity of theliquid fuel.